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Date: Thu, 20 Dec 2018 16:55:00 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: Roberto Sassu <roberto.sassu@...wei.com>
Cc: zohar@...ux.ibm.com, david.safford@...com, monty.wiseman@...com,
linux-integrity@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v7 1/5] tpm: dynamically allocate the allocated_banks
array
On Thu, Dec 13, 2018 at 11:29:41AM +0100, Roberto Sassu wrote:
> This patch renames active_banks (member of tpm_chip) to allocated_banks,
> stores the number of allocated PCR banks in nr_allocated_banks (new member
> of tpm_chip), and replaces the static array with a pointer to a dynamically
> allocated array.
>
> tpm2_get_pcr_allocation() determines if a PCR bank is allocated by checking
> the mask in the TPML_PCR_SELECTION structure returned by the TPM for
> TPM2_Get_Capability(). If a bank is not allocated, the TPM returns that
> bank in TPML_PCR_SELECTION, with all bits in the mask set to zero. In this
> case, the bank is not included in chip->allocated_banks, to avoid that TPM
> driver users unnecessarily calculate a digest for that bank.
>
> One PCR bank with algorithm set to SHA1 is always allocated for TPM 1.x.
>
> As a consequence of the introduction of nr_allocated_banks,
> tpm_pcr_extend() does not check anymore if the algorithm stored in tpm_chip
> is equal to zero.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
> drivers/char/tpm/tpm-chip.c | 1 +
> drivers/char/tpm/tpm-interface.c | 18 +++++++++--------
> drivers/char/tpm/tpm.h | 3 ++-
> drivers/char/tpm/tpm1-cmd.c | 10 ++++++++++
> drivers/char/tpm/tpm2-cmd.c | 34 ++++++++++++++++++++++----------
> 5 files changed, 47 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 32db84683c40..ce851c62bb68 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -160,6 +160,7 @@ static void tpm_dev_release(struct device *dev)
> kfree(chip->log.bios_event_log);
> kfree(chip->work_space.context_buf);
> kfree(chip->work_space.session_buf);
> + kfree(chip->allocated_banks);
> kfree(chip);
> }
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index d9439f9abe78..7b80919228be 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -488,8 +488,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
> int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
> {
> int rc;
> - struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
> - u32 count = 0;
> + struct tpm2_digest *digest_list;
> int i;
>
> chip = tpm_find_get_ops(chip);
> @@ -497,16 +496,19 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
> return -ENODEV;
>
> if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> - memset(digest_list, 0, sizeof(digest_list));
> + digest_list = kcalloc(chip->nr_allocated_banks,
> + sizeof(*digest_list), GFP_KERNEL);
> + if (!digest_list)
> + return -ENOMEM;
You could preallocate digest list and place it to struct tpm_chip
instead of doing it everytime tpm_pcr_extend() called.
>
> - for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> - chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
> - digest_list[i].alg_id = chip->active_banks[i];
> + for (i = 0; i < chip->nr_allocated_banks; i++) {
> + digest_list[i].alg_id = chip->allocated_banks[i];
> memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
> - count++;
> }
>
> - rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
> + rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_allocated_banks,
> + digest_list);
> + kfree(digest_list);
> tpm_put_ops(chip);
> return rc;
> }
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index f27d1f38a93d..6b94306ab7c5 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -257,7 +257,8 @@ struct tpm_chip {
> const struct attribute_group *groups[3];
> unsigned int groups_cnt;
>
> - u16 active_banks[7];
> + u32 nr_allocated_banks;
> + u16 *allocated_banks;
> #ifdef CONFIG_ACPI
> acpi_handle acpi_dev_handle;
> char ppi_version[TPM_PPI_VERSION_LEN + 1];
> diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
> index 6f306338953b..0874743ca96d 100644
> --- a/drivers/char/tpm/tpm1-cmd.c
> +++ b/drivers/char/tpm/tpm1-cmd.c
> @@ -709,6 +709,16 @@ int tpm1_auto_startup(struct tpm_chip *chip)
> goto out;
> }
>
> + chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
> + GFP_KERNEL);
> + if (!chip->allocated_banks) {
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + chip->allocated_banks[0] = TPM2_ALG_SHA1;
> + chip->nr_allocated_banks = 1;
> +
> return rc;
> out:
> if (rc > 0)
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index a6bec13afa69..245669a7aba5 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -234,7 +234,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
> int i;
> int j;
>
> - if (count > ARRAY_SIZE(chip->active_banks))
> + if (count > chip->nr_allocated_banks)
> return -EINVAL;
>
> rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
> @@ -825,11 +825,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> void *marker;
> void *end;
> void *pcr_select_offset;
> - unsigned int count;
> u32 sizeof_pcr_selection;
> + u32 nr_possible_banks;
> + u32 nr_alloc_banks = 0;
> + u16 hash_alg;
> u32 rsp_len;
> int rc;
> int i = 0;
> + int j;
>
> rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
> if (rc)
> @@ -844,11 +847,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> if (rc)
> goto out;
>
> - count = be32_to_cpup(
> + nr_possible_banks = be32_to_cpup(
> (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
>
> - if (count > ARRAY_SIZE(chip->active_banks)) {
> - rc = -ENODEV;
> + chip->allocated_banks = kcalloc(nr_possible_banks,
> + sizeof(*chip->allocated_banks),
> + GFP_KERNEL);
> + if (!chip->allocated_banks) {
> + rc = -ENOMEM;
> goto out;
> }
>
> @@ -857,7 +863,7 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
> end = &buf.data[rsp_len];
>
> - for (i = 0; i < count; i++) {
> + for (i = 0; i < nr_possible_banks; i++) {
> pcr_select_offset = marker +
> offsetof(struct tpm2_pcr_selection, size_of_select);
> if (pcr_select_offset >= end) {
> @@ -866,17 +872,25 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> }
>
> memcpy(&pcr_selection, marker, sizeof(pcr_selection));
> - chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg);
> + hash_alg = be16_to_cpu(pcr_selection.hash_alg);
> +
> + for (j = 0; j < pcr_selection.size_of_select; j++)
> + if (pcr_selection.pcr_select[j])
> + break;
> +
> + if (j < pcr_selection.size_of_select) {
> + chip->allocated_banks[nr_alloc_banks] = hash_alg;
> + nr_alloc_banks++;
> + }
The same comment as before: you should use memchr_inv() here.
> +
> sizeof_pcr_selection = sizeof(pcr_selection.hash_alg) +
> sizeof(pcr_selection.size_of_select) +
> pcr_selection.size_of_select;
> marker = marker + sizeof_pcr_selection;
> }
>
> + chip->nr_allocated_banks = nr_alloc_banks;
> out:
> - if (i < ARRAY_SIZE(chip->active_banks))
> - chip->active_banks[i] = TPM2_ALG_ERROR;
> -
> tpm_buf_destroy(&buf);
>
> return rc;
> --
> 2.17.1
>
/Jarkko
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